Using differential forms---within SageManifolds

Hi all.

I'm aware of the implementation of DifferentialForms within SageManifolds, but I'd like to know how could I use this forms with ease.

In the Sage Reference Manual_Manifolds, there are examples of AffineConnection and the connection_form. However, it seems that the last (connection_form) does not allow to store the calculations, like for example:

nab = g.connection() ## This works for the usual connection
nab.display()
omega = nab.connection_form() ## DOES NOT work, one needs to specify components

I would like to calculate all the components of the connection form, to be able of compute covariant exterior derivatives of other objects.

How can the connection, curvature and torsion forms be stored (as differential forms)?